A cost function for the natural gas transmission industry: further considerations

This article studies the cost function for the natural gas transmission industry. In addition to a tribute to H.B. Chenery, it firstly offers some further comments on a recent contribution (Yépez, 2008): a statistical characterization of long-run scale economies, and a simple reformulation of the long-run problem. An extension is then proposed to analyze how the presence of seasonally-varying flows modifies the optimal design of a transmission infrastructure. Lastly, the case of a firm that anticipates a possible random rise in its future output is also studied to discuss the optimal degree of excess capacity to be built into a new transmission infrastructure

Absorber design in sour natural gas treatment plants: Impact of process variables on operation and economics = Absorberentwurf für Anlagen zur Behandlung von sauren Erdgasen: Einfluss Prozessparameter auf Betriebsführung und Prozesswirtschaftlichkeit

Two models of absorber have been developed which describe the absorption of H2S and CO2 from natural gases by aqueous di-isopropanolamine (DIPA) or methyl-di-ethanolamine (MDEA) solutions. In these models mass transfer, reaction and equilibrium processes as they prevail in conventional tray absorbers and in cascades of trickle bed reactors are incorporated. Owing to the better mass transfer characteristics of the latter type of absorber, i.e. the larger ratio between the gas phase and liquid phase mass transfer coefficients, kg/kℓ, higher selectivities for the absorption of H2S from sour natural gases are realized.\ud \ud The influence of variation of a number of operation and design parameters on tray absorber performance, H2S selectivity and solvent flowrate is demonstrated.\ud \ud The economics of the above type of absorbers together with a solvent regenerator, sulfur recovery unit and tail-gas unit are explained in detail. From the point of view of the economics trickle bed absorbers are very attractive owing to lower investment costs and higher selectivities, which result in lower operating costs than for tray absorbers under identical conditions